1. Field of the Invention
The present invention relates generally to tactile display apparatus, and, more particularly, to an electromechanical system for selectively displaying and erasing information from a reference surface.
2. Description of the Prior Art
A particularly desirable application for the invention concerns the presentation of the Braille character set for visually impaired people. However, there are numerous other applications for the invention.
For example, a large matrix of tactile display units could be employed to display numbers, letters, and figures as raised patterns in devices that provide viewing screens for the visually impaired. The sighted can also benefit from the invention. For example, tactile display units can be utilized singularly or in groups as displays on operating consoles for limited or low light conditions such as aircraft, mining equipment, and military hardware where the raised patterns can be utilized as nonvisual indicators.
Braille was devised to enable the visually impaired to read alpha-numeric characters and is in the form of a six unit code, where each cell represents a character or symbol. Thus, with a six unit code in each cell, there is a matrix of two columns with three in a column. By employing a six unit code, a maximum of sixty-four combinations can be created for which include the twenty-six letters of the alphabet, the numbers zero and one through nine, and various symbols such as case indicators, punctuation, and so forth.
A tactile display unit of the type which will be described in detail below is one which provides for the raising and lowering of a physical point above a plane of reference in such a manner that the change of state from one position to another, that is, from a raised position to a lowered position, or vice versa, is physically detectable by the sense of touch. Numerous mechanisms have been devised to provide such tactile displays. They have generally been large, complex, cumbersome, and expensive to construct, operate, and maintain. Many have been patented. Typical of patents which disclose such devices utilizing magnetically operable pins or solenoids are U.S. Pat. Nos. 3,395,247; 3,510,967; 3,592,965; 3,987,438; 4,033,053; 4,178,586; 4,191,945; and 4,194,190. Other typical patents disclose a variety of other mechanisms for achieving a similar result. For example, U.S. Pat. No. 2,891,324 discloses a mechanism which utilizes piano-like rolls; U.S. Pat. Nos. 4,044,350 and 4,473,356 disclose piezoelectric reeds; U.S. Pat. No. 4,586,904 discloses magnetically operable balls; U.S. Pat. No. 4,215,490 discloses mechanical linkages; U.S. Pat. No. 4,266,936 discloses bimetallic latches; and U.S. Pat. Nos. 4,445,871 and 4,586,903 disclose the use of continuous belts. Because of their complexity, most of these known devices are expensive to manufacture, thereby resulting in an end product with a cost that is prohibitive to many consumers. Also, the power requirements of some of these devices require drive levels that are beyond the capability of most target units without the addition of a supplemental power supply.
The present invention is a direct descendant of U.S. Pat. No. 4,871,992 in which the up and down motion of a touch pin is achieved by driving a cam with small positive and negative voltages. Simple decoding circuitry assigns positive voltages to a bit that is in the high (logical 1) state and a negative voltage to a bit that is in the low (logical 0) state. In a computer Braille example, a eight bit data bus would be established to drive all eight touch pins of a tactile display unit, which are arranged in a 2xc3x974 matrix simultaneously. This is a departure from standard Braille which is comprised of six touch pins arranged in a 2xc3x973 matrix. The present invention can support these and any other number and arrangement of pins. These high and low signals alternately supply positive and negative voltages to an electromagnet located below the cam. Embodied in the cam is a permanent magnet which would be repelled by the electromagnetic force. By the construction of the device, this action would force the cam to rotate about its axis to position the pin at the desired point. The high point of the contour on the cam would desirably have a small depression in which the pin can temporarily come to rest. Due to its design, however, the lower portion of the cam does not require an additional depression. Under the bias of a spring on the pin, the cam as well as the pin remain mutually in their desired positions until an opposite voltage is applied. This arrangement provides a latching mechanism for the device. The electrical current resulting from the drive voltages and the pulse duration is sufficient to force the cam out of its xe2x80x9clatchedxe2x80x9d position to the desired state without a constant voltage being applied to maintain the desired state. The entire disclosure of U.S. Pat. No. 4,871,992 is hereby incorporated into this specification in its entirety.
It was with knowledge of the prior art as just described and with the goal of improving upon known technology that the present invention was conceived and has now been reduced to practice.
The present invention relates to a tactile display system which includes a housing containing a tactile pin movable axially transverse of a reference surface and an actuator mechanism engageable with the tactile pin for its selective movement between raised and lowered positions. An elongated electromagnet distant from the reference surface is aligned with the tactile pin and has spaced poles of opposite, selectively reversible, polarity. A generally spherical rotatable positioning member being a permanent magnet having a peripheral surface which is partially a spherical surface and partially a truncated surface has an axis of rotation coaxial with the tactile pin and the electromagnet and is responsive to operation of the electromagnet, being movable between a first position at which the spherical surface faces the tactile pin, causing positioning of the tactile pin at the raised position and a second position at which the truncated surface faces the tactile pin causing positioning of the tactile pin at the lowered position.
Depending on the desired application, the apparatus of the invention could be fabricated in a variety of sizes. In the instance of a Braille character display, for example, a size would be chosen that would allow a two-by-three matrix of tactile display devices to be packaged to provide a Braille character readout at the same scale as an embossed Braille text.
In a computer Braille application, each tactile display unit is preferably configured into a two-by-four matrix of these tactile display devices. By arranging these units into a matrix not unlike core memory or a computer keyboard, a series of these units can be addressed with a minimum of internal decoding and driver circuitry.
An ASCII character is translated into a eight bit computer Braille representation and transmitted along the rows and columns of the matrix to the proper unit.
One application of the invention as presented in this disclosure is as a device for representing Braille characters. However, any touchable type of display that utilizes a matrix of pins to represent numbers, letters, or figures could gain a benefit from this device. Other possible applications include computer CRT repeaters, adding machine displays, electronic clocks, digital thermometers, elevator floor indicators and any other device that utilizes digital display technology. The ultimate goal of the invention is to provide a design that will result in the fabrication of a low-cost, low power device that employs a simple mechanism to display tactile data that ensures a long life span for each component.
Primary features of the invention, then, include its compact, durable, and simplified design utilizing a minimum of moving parts and commonly available materials. It is inexpensive to manufacture and maintain and is capable of achieving a long life span. Additionally, its modular design enables an end use to employ as many or as few tactile display devices or units as necessary.
Another feature of the present invention is the provision of a tactile display system which operates to selectively display and erase information from a reference surface.
Still another feature of the present invention is the provision of such a tactile display system which includes a tactile pin movable axially in directions transverse of the reference surface between raised and lowered positions and an actuator mechanism engageable with the tactile pin for selectively moving the tactile pin between the raised and lowered positions.
Yet another feature of the present invention is the provision of such a tactile display system for which the actuator mechanism includes an elongated electromagnet distant from the reference surface having first and second spaced poles of opposite, selectively reversible, polarity, the longitudinal axes of the tactile pin and the electromagnet being mutually aligned.
Still a further feature of the present invention is the provision of such a tactile display system for which the actuator mechanism includes a generally spherical rotatable positioning member having an axis of rotation coaxial with the longitudinal axes of the tactile pin and of the electromagnet, the rotatable positioning member being a permanent magnet having a peripheral surface which is partially a spherical surface and partially a truncated surface, the positioning member being responsive to operation of the electromagnet and being movable between a first position at which the spherical surface faces the tactile pin and causes positioning of the tactile pin at the raised position and a second position at which the truncated surface faces the tactile pin and causes positioning of the tactile pin at the lowered position.
Yet a further feature of the present invention is the provision of such a tactile display system in which the electromagnet is intermediate the tactile pin and the rotatable positioning member.
Still another feature of the present invention is the provision of such a wherein the rotatable positioning member is intermediate the tactile pin and the electromagnet.
Other and further features, advantages, and benefits of the invention will become apparent in the following description taken in conjunction with the following drawings. It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory but are not to be restrictive of the invention. The accompanying drawings which are incorporated in and constitute a part of this invention, illustrate one of the embodiments of the invention, and together with the description, serve to explain the principles of the invention in general terms. Like numerals refer to like parts throughout the disclosure.